1. Introduction

The TOAR data portal is a central access point for a variety of ozone data. Users can access data through the portal, contribute additional resources to it, or engage in the TOAR-II activity of the International Global Atmospheric Chemistry (IGAC) project.

Fig. 1.1 User Interaction with the components of the TOAR data portal

Figure 1 shows the five categories of data provided by the portal: satellite, aircraft, surface, and ozone sondes and LiDAR sensors measured data as well as TOAR related data publications. Links to data collections in these categories are provided. Users are welcome to provide links to other repositories. For the surface data, which is collected and harmonised in the TOAR database by JSC, users can contribute measured surface data to be included in the TOAR database. Except for the surface data all other data sources are the responsibility of the respective organisations. The portal also offers to contribute to TOAR science by joining the group and analysing data to support the ozone assessment report under development. Published data sets compiled for these analyses can be accessed through a link provided by the TOAR data portal. In the following, the functions of the TOAR data portal are explained in more detail.